Nichrome spiral: properties, application

Modern life can not be imagined without a huge number of various electrical appliances. For many of them, the nichrome spiral is the main part - the "heart" of the mechanism. The work of electronic devices, machines, power tools used in everyday life and large-scale production, directly depends on the wire with the original alloy.

Description

In 1905, the American scientist Albert Marsh came up with the idea of combining chrome and nickel. The patented formula looked like 20% chromium and 80% nickel. The alloy was called nichrome. Initially, there was no ligature (refractory elements) in the mixture and it was a two-component alloy. Today, you can find variants with a nickel content of 55%, and chromium of 15%. Admixtures are: iron, silicium, manganese, aluminum, titanium, molybdenum, silicon. There are more than ten "recipes" of metal, falling under the designation of nichrome.

The nichrome spiral, having an exceptionally high specific resistivity, has become an indispensable component in numerous instruments and instruments. It is capable of withstanding high-temperature oxidation under both normal and aggressive conditions. This property is due to the presence of chromium, which forms a protective oxide film on the surface of the product. She also stains the alloy in a dark color. If the oxidized layer is removed (by mechanical action), the shade changes to whitish-gray.

The two-component alloy has no magnetic characteristics, multicomponent modifications can have weakened parameters. The nihromic spiral differs rigidity and good plasticity. The wire is produced with a different cross-section from 0.01 to 10 mm. Basic properties:

• Specific electrical resistance - 1100-1400 OM`m;
• Melting temperature up to 1400 degrees (operating range - 800-1100 degrees Celsius);
• Density - 8200-8500 kg / m ³ ;
• Strength - 650-700 MPa.

The properties of the material correspond to the highest technological requirements.

Benefits

The high and steady demand for components from nichrome is due to the amazing qualities of the alloy:

• Not exposed to corrosion;
• Has a small weight;
• Easy to handle (easily stamped and welded);
• Has high heat resistance;
• Strong and at the same time elastic;
• Differs increased resistance to aggressive media;
• Has a long service life.

Another important advantage is the increased resistance to electric current. In practice, this figure allows for a smaller amount of nichrome (the length of the nichrome spiral is shorter) to get more heat than from, for example, a steel element. In turn, a smaller amount of metal can reduce the weight and size of the entire apparatus. The most important advantage of Nichrome is the combination of all of the above indicators in one material.

Varieties

The nihromic spiral can be made of various modifications of the alloy and be of different thicknesses. The brands differ in their composition and are divided (conditionally) into three main groups:

• For resistors: Х20Н80 (20% chromium, 80% nickel); X20H73YUM-VI (20% chromium, 73% nickel, 3%, aluminum, 1.5%, molybdenum, up to 0.3% manganese, up to 0.05%, titanium, 2%, iron, up to 0.05% carbon , Melted vacuum-induction method).
• For use at temperatures not exceeding 900 degrees.
• For heating elements with increased resistance to high temperatures: ХН70Ю-Н (27% chromium, 70% nickel, 3% aluminum, up to 0.3% manganese, up to 0.03% cesium, up to 0.1% barium, up to 1, 5% of iron, up to 0.1% of carbon).

The properties of the alloy depend on the proportions of the constituent components. A large amount of chromium prevents oxidation.

Scope of application

Nichrome wire is one of the most popular materials on the market of electrical products. A spiral made of this alloy is used in many models of electric heaters. At home, the craftsmen use it for:

• The apparatus for burning wood;
• Self-made kilns for ceramic firing;
• Devices for rapid heating of certain metals in the smithy;
• The manufacture of simple heating structures ("goats");
• Self-made welding machines.

Industrial use of nichrome in household appliances is extensive: hair dryers, irons, heating appliances, soldering irons, electric hobs and the like. A wire with a large cross-section is used for automatic welding units. Such an alloy can be found in laboratory equipment and radio engineering. Nichrome is used wherever resistance to high temperatures and corrosive environments is required.